INSTINCT OP NUTRITION, 511 



wound in conjunction, namely, among the wasps, and in the genus 

 Onyderus. I have hitherto neglected to inspect more closely the struc- 

 ture of this threefold sting, but I surmise that in this case the several 

 seta? of which the simple sting consists are more remote from each 

 other, and therefore project separately from the abdomen. 



The stings of the Diptera are not weapons of defence, but organs 

 whereby they may imbibe their nutriment. They are therefore only 

 used for this purpose, and not as a means of defence. Among the 

 Hemiptera, which likewise possess organs of puncture in the mouth, 

 the latter may not be affirmed, for the Notonecta defend themselves 

 with their proboscis, and their puncture, as was before mentioned, is 

 very painful. 



II. INSTINCT OF NUTRITION. 



290. 



The food which insects take is more important to their self preserva- 

 tion than all these means of defence. We have before classed their 

 chief kinds, and can here only make a few observations upon the way 

 in which they procure it. 



In the majority of insects this takes place without much art or 

 exertion, in as far as the insect in its most helpless state, namely, as a 

 larva, finds itself generally in a place where its food is very abundant. 

 It has to thank its mother's care for this, for she lays the eggs mostly 

 where there is food for the larva, or else provides it with food in its 

 cell, in whichshe has enclosed the egg. But these instances do not 

 properly belong here, but to the following chapter, Avhere we shall 

 speak of the means provided for the conservation of the species, and 

 only such facts, as convince us of the instinct of the insect for its 

 independent supply of food, shall here be mentioned. Among our 

 native beetles the larvae of the Cicindelce exhibit these instincts. They 

 dwell in sandy places, where they dig a cylindrical hole by means of 

 their feet and mandibles, wherein they sit. They watch from this place 

 of concealment all insects that pass by, and which heedlessly venture to 

 the margin of the hole, when they fall in, and are then devoured by 

 the larva. Miger, who first observed this larva *, has given a detailed 

 account of its economy. The plan adopted by the larva of the genus 



* Annales du Museum d'Hist. Nat. v. 14. 



